In the vast area of piezo film applications, it is necessary to have a means of detecting the charge or voltage produced by a piezo or pyro event. An electrode is needed on each side of the film for any application. Most such applications require the electrodes on opposite surfaces of the film to be electrically isolated from each other. Thus, care must be observed when depositing the electrodes on film surfaces to insure that metal migration does not occur over the edges of the film to result in possible shorting out of the electrodes. It is sometimes necessary however to electrically connect an electrode on one film surface with an electrode on the opposing film surface or to an electrode on the surface of another film to control capacitance or impedance; to effect common electrical connection; to move a conductor from one film surface to another surface; to permit ease of lead attachment for termination, and the like.
The present invention provides a facile and convenient method for electrically connecting electrodes on opposing surfaces of a piezoelectric film by forming at least one hole or channel through the film as well as the lead to be electrically connected or linked to another surface. The hole may be formed by pin, punch, or laser, for example. Then, by depositing conductive ink over the hole by silk-screening, for example, a portion of the ink will adhere to the hole sidewalls while penetrating the hole to effect the electrical connection with the pierced electrode.
If it is desired to electrically move an electrode from the surface of one film to the surface of another film, it is only necessary to align the films, pierce the film whose surface is to be linked to the already deposited electrode, and silk-screen conductive ink over the pierced hole or channel.
The invention is not intended to be limited to silk-screening processes for depositing a conductive ink over the hole, but may employ electrostatic printing and xerography techniques, spraying, painting, ink jet printing, carbon particle deposition, and the like.